Nitrogen containing rho-tert-butylstyrene copolymers

ABSTRACT

HIGH MOLECULAR WEIGHT NITROGEN-CONTAINING COPOLYMERS OF P-TERT-BUTYLSTYRENE AND LUBRICATING OIL CONTAINING THEM.

United States Patent ()fice 3,752,794 Patented Aug. 14, 1973 3,752,794 NITROGEN-CONTAINING p-TERT-BUTYL- STYRENE COPOLYIVIERS Robert Bacskai, Kensington, Califi, assignor to Chevron carbon type such as ethylene chloride. In the suspension and emulsion processes the monomer mixture is dispersed in an aqueous medium sometimes with the aid of a surfactant. In general, the accepted procedures of the prior Research p y, San Francisco Cam, 5 zfirt for the preparation of styrene copolymers are satls No Drawing. Original application Dec. 10, 1969, Ser. No. acmry- 886,383 Divided and this applicafim Jam 12, 1972 The copolymers of p-tert-butylstyrene of the 1nvent1on sen 217 237 have average molecular weights of at least about 20,000 Int C08f 15/04 as determined by standard light-scattering methods. For US, Cl, 260-88.1 PA 5 Claims 10 present purposes the preferred copolymers have average molecular weights in the range of from about 50,000 to about 1,000,000 and a solubility in mineral lubricating ABSTRACT OF THE DISCLOSURE oil of at least about 0.1% by Weight. High molecular Weight nitrogen-containing copolymers The nitrogen-containing monomers in the p-tert-butyl- 0t petel't'butylstyr em? and lubricating Oil containing themstyrene copolymers according to the invention are present in minor proportions sufficient to impart polarity and dispersing characteristics to the copolymers in hydrocarbon 17,1971 2.. if??? viefigiffa fi $?.ii$iii35332.1???)Z 11;

. 0 i 0 BACKGROUND OF THE INVENTION weight. l'he quantity of nitrogen-containing monomer in This invention relates to novel high molecular weight th opo1ymers f thi invention i il does not nitrogen-containing copolymers of py y and ceed about 10% by weight since at this point the copolylllblicatiflg Oils containing them as ViSCOSitY index P mer becomes insoluble in hydrocarbon lubricating oils. il'lg diSPBISaIItS- Preferably the nitrogen-containing monomer does not Oil-soluble high molecular weight polymers are useful amount t more th n bo t 5% by weight of the in a variety of applications. They are widely used as thickopo1ymer fillers in comPositions Such as Paint and the likey are The following examples are further illustrative of the also used as thickeners for fuel compositions 01' as ViS- nitrogen-containing copolymers of p-tert-butylstyrene accosity index imPIOWrs in lubricating Oil compositionscording to this invention. Unless otherwise specified, the Soluble g molecular Weight P y containing Polar proportions in the illustrative examples are on a weight groups find utility as dispersants for paints, fuels, lubrib i cants and other compositions. (I) Bulk copolymers SUMMARY OF THE VENT The copolymerization of p-tert-butylstyrene with 4- It has now been found that copolymers of p-tert-butylvinylpyFidine (441p) was 4 in bulk using Yarious styrene and nitrogen-containing monomer selected from 13201101110118 reactants' T reactlon? were camed out group consisting of 4 viny1pyridine and N viny1pyr with free radical catalyst in vacuum in degassed, sealed rolidone, said copolymer having an average molecular Py tubes- The catalyst used was gaZOISObIItYrO- weight as determined by standard 1i -i meas- 40 mtrile and the reaction was at 70 C. for 16.5 hours. Folurements in the range of from about 20,000 toabout lowing polymerizatlen the Py tubes were opened and 1,000,000 and a solubility in mineral lubricating oil of at the Solid Products dissolved in hexane, then Precipitated least about 0.1% by weight, are efiective as thickening into methanol- The P y precipitate Was filtered, and dispersing agents, more specifically as viscosity index shed With methanol and dried at 70 C. in vacuum. improvers and dispersants in oils of lubricating viscosity. These examples are summarized in the following table:

TABLE I Monomers Polymer 4-VP Butyl 4-VP Specific styrene, Wt, Yield, wt., viscosity, Example No; g. G. percent g. percent percent flap/u- DESCRIPTION OF THE PREFERRED EMBODIMENTS The copolymers of p-tert-butylstyrene and 4-vinylpyridine or N-vinylpyrrolidone are prepared by any one of the Well known mass, suspension, solution or emulsion copolymerization processes. The preferred method of preparation is via the emulsion polymerization process. In all of these processes the monomers are mixed in the desired ratio, a free radical initiator is added, and the entire mixture is heated to effect copolymerization.

In mass or bulk copolymerizations the process is carried out in the absence of any diluent. In the solution polymerization process the monomers and catalyst are dissolved in a solvent of the aliphatic or aromatic hydrocarbon type such as benzene or of the chlorinated hydro- (II) Solution copolymers The copolymerization of p-tert-butylstyrene with 4- vinylpyridine and N-vinylpyrrolidone was conducted in solution. In these examples the copolymerization was carried out in a 3-necked stirred flask under nitrogen. The solvent was either 130 Neutral oil, a California paraffin-base oil having a viscosity of 130 SSU at F., or hydrocarbon, as noted in the following table summarizing these examples. In the case of the Neutral oil 3 solvent, unreacted monomer was removed by vacuum distillation and the reaction product was diluted with additional oil to give 2.8 weight percent polymer for further testing. In the case of the hydrocarbon solvents, the copolymer was isolated by pouring the reaction mixusually not more than about 10.0% by weight, as an upper limit.

In the lubricating oil compositions of this invention the p-tert-butylstyrene copolymer thickeners and dispersants are used with lubricating oil base in an amount sufiicient ture into methanol and filtering and drying the product. to raise the viscosity index and/or improve the detergent TABLE II Polymerization conditions Polymer N" monomer Bum Wt Cat 1 st Time Temp Yield 82 1 st e, a y 1 1 53 8 g. G. percent Solvent (grams) (grams) hr. 0. g percent percent "ML/C 5 32. 94 1 1. 1 3. 64 130 neutral (74.05) AIBN (0.1752) 4.? G 33. 0 1 1. 27 9 3. 71 130 neutral (74.20) AIBN (0.1758)- 4.513 7 33.02 1 1.25 1 3.65 Benzene (73.86) AIBN (0.34) 16. 0. 63 3.67 Benzene (39.07) IPP (0.l7) 19:7 3: 33.10 1 1.25 1 3. 64 n-Heptane (73.84)-.-" AIBN (0.34) U} l -VP. 2 N-VP.

In the above Table H the N monomer is either 4-vinylpyridine or N-vinylpyrrolidone, as denoted by the abbreviations l-VP and N-NP, respectively. The free radical catalyst is azoisobutyronitrile (AIBN) or isopropyl percarbonate (IPP), as indicated.

(III) Emulsion copolymers The emulsion copolymerization of p-tert-butylstyrene with 4-vinylpyridine or N-vinylpyrrolidone was carried out under conditions similar to those reported previously for the polymerization of styrene by Sorenson and Campbell, Preparative Methods of Polymer Chemistry, Interscience, 1961, page 162. The reaction was conducted under nitrogen in a 3-necked stirred flask using free radical initiator. After polymerization the emulsion was poured into acetone, filtered and washed, and filtered repeatedly with distilled water. The copolymer residue was dried in vacuum at 70 C. The amount of recovered polymer was approximately theoretical value. The molecular weight of the copolymer was varied by adjusting the amount of the chain transfer agent (tertdodecylmercaptan) as shown by the variation in the specific viscosity.

In each of the experiments 15 g. of p-tert-butylstyrene as described above and 0.4 g. of the N monomer were reacted in 50 g. of distilled water along with 0.025 g. Na HPO 0.05 g. K S O and 0.5 g. of the sodium lauryl sulfate. The reaction was conducted at 70 C. for about two hours and then at 95 C. for about two hours.

.Table III provides a summary of these examples.

TAB LE III Monomer teed Polymer l [N I I l t N I J monomer, t-Dodecyl monomer, Example wt. mercaptan, wt. No. percent percent percent percent 1 .10.

As shown by the above data, i.e., the specific viscosity,

about 0.1% by weight based on the total composition,

properties of the base lubricating oil. Ordinarily amounts of the copolymers of from about 0.1% to about 10% by weight, preferably from about 1.0% to about 5.0% by weight, are satisfactory for this purpose. In view of the excellent solubility characteristics of the copolymers, a further feature of the invention lies in the preparation of lubricating oil concentrates containing percentages of polymers of up to about 10% by weight.

The base oil in the lubricant composition of the invention is any oil of lubricating viscosity. Thus, the base oil can be a refined parafiin-type base oil, a refined naphthenic-type base oil, or a synthetic hydrocarbon or synthetic nonhydrocarbon oil of lubricating viscosity. As synthetic oils, suitable examples include oils obtained by polymerization of lower molecular weight alkylene oxides, such as propylene oxide and/or ethylene oxide employing alcohol or acid initiators, such as lauryl alcohol or acetic acid. Still other synthetic oils include esters, e.g., di-(2- ethylhexyl)-sebacate, tricresylphosphate and silicate esters, such as tetra-(Z-ethylhexyl)-orthosilicate and hexa-(2- ethylbutoxy)-disiloxane. For present purposes the mineral lubricating oils are preferred, since they show the greatest viscosity, detergency and stability improvement.

Lubricant compositions Within the scope of the present invention may also contain still other additives of conventional types, such as pour point depressants, oiliness and extreme pressure agents, anti-oxidants, blooming agents and the like. Other types of detergents, such as metal salts, may also be employed where ash formation is not a problem.

Illustrative lubricant compositions of the aforementioned types containing additives other than the polymeric additive may include, for example, from about 0.1 to about 10% by weight of alkaline earth metal, higher alkyl phenate detergent and wear reducing agents such as the calcium alkylphenate having mixed alkyl groups of 12 to 15 carbon atoms. They may also include from about 0.1 to 10% by weight of organic thiophosphate corrosion and high-temperature oxidation inhibitors, such as the reaction product of pinene and P 8 the reaction product of polybutene and P S and the bivalent metal dihydrocarbon dithiophosphates, zinc butyl amyl dithiophosphate and zinc di-(tetradecylphenyl) dithiophosphate. Metal salt detergents in amounts from about 0.1 to 10% which may also be used are the calcium petroleum sulfonates of the oil soluble mahogany type and the calcium naphthenates.

The outstanding characteristics of the lubricating oil composition containing the copolymers in accordance with this invention are shown in various tests. In these tests viscosities of the compositions were determined and the viscosity index calculated by the Standard ASTM Method D567-41. The detergent or dispersant properties of the copolymers were determined by measuring the ability of the lubricating oil composition containing the polymer to disperse a synthetic resin in standard hydrocarbon solvent, the synthetic resin being a simulation of the resins naturally ocurring in internal combustion engines. Compositions effective as dispersants were rated while those not effective were rated In the tests, 2.8% by weight of the polymer was dissolved in 130 Neutral oil, which is a California paraflin base oil having a viscosity of 130 SSU at 100 F. This base oil ordinarily has a viscosity index of 89 and a dispersant rating The tests of the copolymers of p-tert-butylstyrene in lubricating oil compositions are summarized in the following table:

In the above Table IV, Examples A and B are p-tertbutylstyrene homopolymers commercially accepted as viscosity index improvers for mineral lubricating oils and are included for the purpose of comparison with the copolymers according to the present invention.

The test results show that the copolymers of p-tertbutylstyrene and nitrogen-containing monomer in accordance with the present invention possess surprisingly good viscosity index improving properties and are effective as dispersants in hydrocarbons as illustrated by the detergent lubricating oil compositions.

In the foregoing examples of copolymer of p-tertbutylstyrene and nitrogen-containing monomers other vinyl pyridines may be used along with or instead of the 4-vinylpyridine. Such alternative vinyl pyridines include the different position isomers and alkyl substituents thereof such as 2-vinylpyridine, S-Vinylpyridine, 2-vinyl- 6-methylpyridine, 4-vinyl-6-ethylpyridine, 2-vinyl-4-iso propylpyridine, 4-isopropenylpyridine, and the like. For present purposes the preferred vinylpyridine is 4-vinylpyridine of the examples in view of the eifectiveness of the copolymers prepared therefrom.

As will be evident to those skilled in the art, various modifications on this invention can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the following claims.

I claim:

1. The random copolymer of p-tert-butylstyrene and nitrogen-containing monomer selected from the group consisting of vinylpyridine and N-vinylpyrrolidone, said copolymer having an average molecular weight as determined by standard light-scattering measurements in the range of from about 20,000 to about 1,000,000 and a solubility in mineral lubricating oil of at least about 0.1% by weight, said nitrogen-containing monomer being from about 0.1 to 10% inclusive by weight of the copolymer.

2. The copolymer of claim 1 having an average molecular weight in the range of from about 50,000 to about 1,000,000.

3. The copolymer of claim 1 in which the nitrogencontaining monomer is from about 0.1 to 5.0% inclusive by weight of the copolymer.

4. The copolymer of claim 1 in which the nitrogencontaining monomer is vinylpyridine.

5. The copolymer of claim 1 in which the nitrogencontaining monomer is N-vinylpyrrolidone.

References Cited UNITED STATES PATENTS 3,561,035 3/19'72 Atkins 26088.1 P

HARRY WONG, 1a., Primary Examiner US. Cl. X.R. 252-50, 51 

